In the treatment of human body malfunctions, for example, it is frequently necessary to electrically stimulate body tissue in order to produce some desirable effect. For example, and as is well-known, the human heart can be stimulated electrically to beat at a proper rate or the cerebellum can be stimulated to inhibit epileptic seizures. In such prior art tissue stimulator applications, the implantable electrode structure that interfaces between the electrical source (pulse generator) and the human tissue to be stimulated typically employ electrodes formed of pure platinum, an alloy of 90% platinum-10% iridium, and Elgiloy.
Where intended for use in an implantable human tissue stimulation unit, it is desirable and often essential that the material from which the stimulation electrode is formed possess certain characteristics. First, the electrode material must be compatible with human tissue and it should develop as little scar tissue as possible to minimize the effect of insulating the electrode surface electrically from the human tissue that is to be stimulated. Secondly, the electrode must not suffer corrosion when implanted in human tissue, nor must it electrolytically decompose when electric current flows through it. Thirdly, it is important that the electrode material have as low a polarization potential as possible so as to minimize the amount of energy dissipated at the electrode/tissue interface. Finally, the overall stimulation electrode unit should be structurally sound so that it retains its form without damage when handled by the implanting surgeon and when place in vivo.